GPS-supported Photogrammetry for Monitoring Deformation of the Brunt Ice Shelf near Halley V Research Station, Antarctica

摘要

The British Antarctic Survey (BAS) Halley-V Research Station is on the Brunt Ice Shelf, Antarctica. The floating ice shelf is about 100 km by 60 km and about 200 m thick. It is flowing towards the sea at about 400 m per year. A key feature of the ice shelf is the McDonald Ice Rumples (MIR), a 3 km by 1 km area where the ice shelf is grounded on the sea-bed, about 20 km from the station. The last major calving event (1967-71) started from cracks that formed here. The subsequent release of the ice shelf from grounding at the MIR led to its acceleration to 800 m per year and formation of several wide rifts between the station and the continent margin. The ice shelf is now developing similar cracks and pressure-ridges to those observed prior to the 1967-71 calving episode. A major new calving event could be a hazard to the BAS Halley station, so it is important to monitor the developing features at the ice rumples. This paper describes an aerial photogrammetric survey to build firstly a detailed DEM as a baseline for monitoring future developments in the MIR features, and secondly, an ortho-image and flythrough to visualise the relationship of the MIR to the surrounding ice-shelf area. Working in this wholly-ice environment, which is unstable, heavily crevassed and inaccessible for ground survey, presented some survey challenges. The most practical method was photogrammetry using GPS-supported aerial photography. However, there are no rock features within 350 km of the MIR for a stable GPS base-station or ground-surveyed control points. Sparse surface texture on the snowy surface in some parts of the survey area caused problems for photogrammetric measurements.